Safety bumper comprising an energy-absorbing element controlled by an impact sensor

ABSTRACT

The safety bumper includes: (a) a bumper basic body ( 4 ) having a forward surface; (b) a bumper bar ( 5 ); (c) a mounting member ( 11 ); (d) a cross-bar ( 10 ) of the vehicle, (e) at least one of a deployable energy-absorbing element ( 9; 32, 33, 39, 41; 52, 60 ) positioned above the mounting member ( 11 ) and a deployable energy-absorbing element ( 17, 20; 38, 46; 64 ) positioned below mounting member ( 11 ); and (f) an impact sensor ( 6 ) located in bumper bar ( 5 ). The bumper bar ( 5 ) is connected to bumper basic body ( 4 ) and extends through to the forward surface of bumper basic body ( 4 ), bumper bar ( 5 ) is also connected to mounting member ( 11 ), and mounting member ( 11 ) is located behind bumper basic body ( 4 ) and bumper bar ( 5 ). The mounting member ( 11 ) is connected to cross-bar ( 10 ), which is located behind mounting member ( 11 ). The deployable energy-absorbing elements are controlled by impact sensor ( 6 ), and upon actuation thereby are deployed and form (either singly or together) a substantially continuous contour and a substantially common front together with the forward surface of bumper basic body ( 4 ).

CROSS REFERENCE TO RELATED PATENT APPLICATIONS

The present patent application claims the right of priority under 35U.S.C. §119 (a)-(d) and 35 U.S.C. §365 of International Application No.PCT/EP00/03159, filed Apr. 10, 2000, which was published in German asInternational Patent Publication No. WO 00/64707 on Nov. 2, 2000, whichis entitled to the right of priority of German Patent Application No.199 18 202.7, filed Apr. 22, 1999.

FIELD OF THE INVENTION

The invention relates to a safety bumper system for motor vehicles, inparticular for private and commercial vehicles, which isconstructionally fashioned in such a way that it meets the requirementsof the current pedestrian protection test, e.g. according to theregulations of the European Enhanced Vehicle Safety Committee (EEVC),but at the same time permits external configuration possibilities as inconventional bumper systems.

BACKGROUND OF THE INVENTION

Known bumper systems of private and commercial vehicles endeavour tosatisfy various requirements with regard to the absorption of energy inthe event of accidents both at low and higher speeds while neverthelessretaining some creative scope for the design. The bumper for the frontor tail region of a private vehicle known from EP 768 213 A2 comprises ashock absorber as an energy-absorbing element, which is connected by aneasily mountable fastening to the actual bumper and to a coveringprovided thereon.

From EP 839 690 A2 a bumper system for commercial vehicles is known,which is composed substantially of combined channel section strips,which have special reinforcing elements. Said bumper system is used, onthe one hand, to absorb energy in the event of collision with othermotor vehicles. On the other hand, with the assembly below an existingbumper an undershoot guard is achieved.

EP 736 420 A2 describes a bumper system for a private vehicle, which hasa bumper substantially comprising an energy-absorbing buffer, which issurrounded by a flexible enclosure and which in the event of a collisiondeforms and in so doing absorbs the kinetic energy.

All known bumper systems are however not capable of meeting the currentrequirements regarding pedestrian protection in the event of an accidentinvolving pedestrians.

In particular, bumper systems are required to satisfy the requirementse.g. of the EEVC (European Enhanced Vehicle Safety Committee) directive.This states i.a. that the impact of a legform impactor—which recreatesthe form of the human leg—with a weight of 13.6 kg and at a speed of 40kph against the front portion of the motor vehicle is to be tested. Theacceleration occurring during the test is to be no greater than 150g/m². The buckling angle of the impactor during the test should notexceed 15° and the shear distance of the impactor parts is to be nogreater than 6 mm.

In addition to the pedestrian protection conditions, it is moreoverdesirable for the bumper system to satisfy the requirements of the 4 kphimpact test and the 8 kph impact test.

There is moreover the need for design freedom to be, as far as possible,only slightly restricted by fulfillment of the EEVC requirements. Theoverall appearance of the motor vehicle is not to be influenced or is tobe influenced only minimally by the protection measures.

SUMMARY OF THE INVENTION

It has been discovered that the new bumper systems described below notonly pass the 4 kph test (optionally also the 8 kph test) but also meetthe above-mentioned pedestrian protection conditions. What is more, byvirtue of the invention, design freedom for configuration of the frontor rear of motor vehicles is extensively retained.

The subject matter of the invention is a safety bumper for a motorvehicle, in particular for a private vehicle, at least equipped with abumper basic body plus bumper bar, which is connected by a mounting, inparticular by an energy-absorbing module as the mounting, to a cross-barof the vehicle, characterized in that above the mountingenergy-absorbing elements and/or below the mounting energy-absorbingelements are provided, which are controllable by an impact sensor, andafter actuation by the impact sensor form above and/or below the bumperbasic body a continuous contour with the front side of the bumper basicbody.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a is a sectional representation of a safety bumper according tothe invention;

FIG. 1b is a sectional representation of the safety bumper of FIG. 1aafter an impact and deployment of the air bags;

FIG. 1c is a sectional representation of a safety bumper similar to thatof FIG. 1a, in which the mounting member (11) is a plastic strut body;

FIG. 2a is a sectional representation of a further safety bumperaccording to the invention with upper and lower lifting systems, and topand bottom sliding plates;

FIG. 2b is a sectional representation of the safety bumper of to FIG. 2aafter an impact and deployment of the lifting systems;

FIG. 3a is a sectional representation of a further safety bumperaccording to the invention with two airbags, in which the lower air bagis located beneath a lowermost part of the bumper; and

FIG. 3b is a sectional representation of the safety bumper of FIG. 3aafter an impact and deployment of the air bags.

DETAILED DESCRIPTION OF THE INVENTION

Here, continuous contour means that in the event of an impact-triggeredactuation of the energy-absorbing elements the latter together with thefront side of the bumper basic body form a common front, which reducethe buckling angle—in relation to the impact of a standard-legimpactor—and keep it e.g. at less than 15°. This then conforms with theprovisions of the initially mentioned guideline of the EEVC.

In a preferred construction, the energy-absorbing element disposed abovethe mounting is an airbag, which is provided in a folded-up state,preferably under a flap, on or behind the mounting and the igniter ofwhich is electrically connected by the control line to the impactsensor.

In a preferred variant, the energy-absorbing element disposed above themounting is an airbag, which is provided in a folded-up state,preferably under a movable top flap, on or behind the mounting and theigniter of which is electrically connected by the control line to theimpact sensor and which together with the opened top flap afteractuation by the impact sensor forms a continuous contour with the frontside of the bumper basic body.

A further special variant of the bumper is characterized in that theenergy-absorbing element disposed above the mounting is a combination ofa top bumper flap, a sliding plate situated below the latter and alifting system plus drive, wherein the drive is electrically connectedby the control line to the impact sensor, and wherein after actuation ofthe drive by the impact sensor the extended top bumper flap and theextended sliding plate (48) form a continuous contour with the frontside of the bumper basic body.

In a preferred construction of the invention, the energy-absorbingelement disposed below the mounting is an airbag, which is provided in afolded-up state, preferably below the lowermost part of the bumper, andthe igniter of which is electrically connected by the control line tothe impact sensor.

A further preferred variant of the bumper is characterized in that theenergy-absorbing element disposed below the mounting is an airbag, whichis provided in a folded-up state, under a movable bottom flap, and theigniter of which is electrically connected by the control line to theimpact sensor and which together with the opened flap after actuation bythe impact sensor forms a continuous contour with the front side of thebumper basic body.

In another special form of construction, the energy-absorbing elementdisposed below the mounting is a combination of a bottom bumper flap, abottom sliding plate situated below the latter and a bottom liftingsystem plus drive, wherein the drive is electrically connected by thecontrol line to the impact sensor, and wherein after actuation of thedrive by the impact sensor the extended bottom bumper flap and theextended bottom sliding plate form a continuous contour with the frontside of the bumper basic body.

The drive for the bottom and/or for the top lifting system isindependently of one another in particular a gas pressure cylinder or ahydraulic cylinder.

Instead of the top or the bottom lifting system an airbag system may beprovided for moving the top or bottom bumper flap.

The said flaps, the top flap, the top bumper flap, the bottom bumperflap or the bottom flap, which hide the energy-absorbing elements fromsight and swing open upon actuation of the sensor, are independently ofone another movably connected by a flexible plastic part, in particularmade of the material TPE or TPU, to the bumper basic body. Conventionalhinges may also be used.

The mounting of the bumper is preferably an energy-absorbing plasticfoam body or plastic strut body.

In a particularly preferred manner the energy-absorbing plastic foambody is made of polyurethane foam or thermoplastic foam material, e.g.polystyrene foam or polypropylene foam.

Particular advantages regarding energy absorption upon impact arise whenthe energy-absorbing elements situated above the mounting and/or theenergy-absorbing elements below the mounting are connected by anadditional supporting strut to the front end of the motor vehicle.

The essential features of the present invention are: the classic bumpersystem is extended in a way that both retains design freedom andsatisfies pedestrian protection requirements.

In principle, the described safety bumper operates as follows: energyabsorption is effected by the outer skin of the bumper system made ofplastics material in conjunction with a constructionally fashionedmounting made of plastics material or metal. This may be a foam systemor a plastic or metal strut body or a combination of both. Said systemis intended to satisfy the requirements regarding the maximumacceleration values.

To satisfy the further requirements regarding pedestrian protection(buckling angle e.g. less than 15° and shear distance e.g. less than 6mm), a swing-out top and bottom part are provided e.g. above and/orbelow the mounting in the outer plastic shell.

Said flap mechanism may be realized by a “hard/soft combination” ofsuitable plastics materials or by the possibilities afforded by theconstruction and/or material of the outer plastic shell alone (hingefunction).

Outward swinging of the top and bottom parts is effected e.g. by meansof fundamentally known airbag systems, mechanical lifting apparatuses orpressure cylinders, which are tripped by pressure sensors and/orcontact-free sensors (radar, ultrasound, laser or the like). Saidsensors should be controlled in particular in a speed-dependent manner.For example, from a vehicle speed of 0 kph up to around 4 kph thesensors do not respond. This serves as a protection against abuse of theairbag systems or against superficial damage.

The flap mechanism may be so designed that the parts involved (flaps)may be reversibly opened and closed a plurality of times.

Materials, which may be considered for the outer bumper shell (frontside), are plastics materials which permit a minimum wall thickness withsimultaneous retention of the mechanical properties over a widetemperature range. For the less rigid components of the swing-open topand bottom flap mechanisms, TPU (thermoplastic polyurethane) or TPE(thermoplastic elastomer) is recommended.

In order to meet the pedestrian protection requirements, besides thealready provided cross-bar additional structural components may beprovided for the purposes of support and stiffening. Said additionalstructural components are preferably realized by plastic/metal compositeparts (e.g. of polyamide+sheet metal). In the event of overload,built-in predetermined buckling points provide crash damage protection.

The invention is described in detail below with reference to thedrawings.

EXAMPLES

Three examples show various forms of construction of the invention.

Example 1 Bumper System

FIGS. 1a and 1 b each show a cross section through a safety bumper.Below the bonnet 1 of a private vehicle a part of the outer boundary ofthe bumper is connected by a hinge 2 to the flap 3. The hinge 2 allowsthe flap 3 to swing open in the direction of the bonnet 1 (as depictedby folded-back flap 18 of FIG. 1b). Selectively, instead of the hinge, aconnecting piece 2 made of elastic material, e.g. a two-componentcompound (a thermoplastic polyurethane: TPU), is provided. A folded-upairbag 9 is provided below the flap 3. The bumper basic body (outerbumper shell) 4 and the bumper bar 5 surround the energy-absorbingmodule (mounting) 11, a polyurethane foam cushion, and a cavity situatedunderneath, in which a further airbag case 14 containing airbag 15 isaccommodated.

The flap 3, the bumper basic body 4 and the bumper bar 5 aremanufactured from a plastics material(polycarbonate/polybuteneterephthalate mixture: PC/PBT) or a polyalcoholformulation. Situated behind the bumper bar 5 is a sensor 6, which viaan electronic signal through the line 12 trips the ignition of theairbags 9 and 15 in the event of a collision with the bumper (theigniters of the airbags 9 and 15 are not illustrated here). Situatedbelow the sensor 6 is a further flap 16, which like the top flap isconnected by a second hinge 7 to the basic body 4 and which may open ina downward direction.

Swinging-open of the flap 16 is likewise tripped via an airbag 15. Theunfolded airbag 17, together with the flap 16 (20 in FIG. 1b) and thecomponents 13 and optionally 22, effects the energy absorption in thebottom region of the bumper and reduces the buckling angle and the sheardistance of the front of the private vehicle.

The airbag 15 is supported via a plastic/metal composite part 13 and 14(of polyamide/sheet steel), which in turn is integrated in the cross-bar10 or at the front end 21 of the car.

The energy absorption in the middle part is effected via a systemcomprising the basic body 4 and the energy-absorbing foam cushion (EAfoam) 11.

In the event of an accident, the unfolded airbag 19 effects the energyabsorption in the region above the bumper and considerably reduces thebuckling angle.

By means of the flap mechanism in the bottom part and by means of theairbag 19, 17 the buckling angle is kept below 15° and the sheardistance is kept at less than 6 mm (see FIG. 1b).

For the additional support of the airbag 15 and the transmission ofimpact energy a further connecting bar 22 may be installed from theairbag 15 to the front end 21 of the car.

In the event of a crash, an anti-overload device in the connecting bar22 provides protection against the destruction or damage of built-onparts. A buckling point may be provided in the form of a bead in theconstruction. A further possibility is the reduction of the bar crosssection by means of through-holes or reduction of the wall thickness.

Example 2

FIGS. 2a and 2 b each show a cross section through an alternative safetybumper. FIG. 2a shows a bumper system, in which in the course of acollision a top lifting system 41 pushes a top flap 32 upwards (flap 49)and a bottom lifting system 46 pushes a bottom flap 38 downwards (flap47).

Provided above the energy absorber 11 is a lifting apparatus 41, whichcarries the top sliding plate 33. The top sliding plate 33 is situatedunder the flap 32, which is movably connected by the elastic hinge 2 tothe bumper basic body 4 and at its top end abuts the bonnet 1.

The bumper bar 5 with the impact sensor 35 is situated on the bumperbasic body 4. Provided below the energy absorber (mounting) 11 is abottom lifting apparatus 46, which carries the bottom sliding plate 47.The sensor 35 is connected by the electrical sensor lines 12 to a topand a bottom gas pressure cylinder 39 and 44, which effect the movementof the lifting apparatuses 41 and 46.

The displacement of the flaps 32 and 38 is triggered by the sensor 35 inthe bumper bar 5 in a similar manner to the triggering of the airbagignition in the bumper system according to Example 1.

The trigger signal is supplied via the sensor lines 12 to movablepressure cylinders 39 and 44. The latter effect the rapid movement ofthe lifting systems 41 and 46. Instead of the lifting systems 41 and 46it is possible to use vertically installed pressure cylinders (notillustrated). A further possibility is displacement of the slidingplates 33 and 38 by means of expanding airbags (not shown).

The energy absorption in the middle part of the bumper is effected as inExample 1.

By virtue of the extending of the bottom flap 32 and the top flap 38 thebuckling angle for an impacting body is kept below 15° and the sheardistance is kept at less than 6 mm (see FIG. 2b).

The materials of the bumper basic body 4 and of the flaps 32 and 38correspond to the materials described in Example 1 (PC/PBT mixture andpolyalcohol formulation). The hinge 2 is made of TPU.

Example 3

FIGS. 3a and 3 b each show a cross section of a further variant of thesafety bumper. FIG. 3a shows a bumper system, in which in the course ofa collision by means of a top and bottom airbag system 60 and 64 a topflap 68 (52) is opened and a uniform impact front is formed.

Provided above the energy absorber 11 is a top airbag system 60, whichis seated below the top flap 68. The top flap 68 is movably connected bythe elastic hinge 2 (made of TPU) to the bumper basic body 4 (made of aPC/PBT mixture) and at its top end abuts the ornamental moulding 58below the bonnet 1.

The bumper bar 5 with the impact sensor 6 is situated on the bumperbasic body 4. Provided below the energy absorber 11 is a bottom airbagapparatus 64, which is disposed under the bottom set-back part of thebumper basic body 4. The sensor 6 is connected by the electrical sensorlines 12 to the top airbag system 60 and the bottom airbag system 64.The bottom airbag system 64 is mounted on the bottom end of a bar 63,which carries the entire bumper and the bottom, externally visible part57 of the bumper. Situated above the part 57 is an air inlet opening.

For the additional support of the airbag 66 and transmission of impactenergy a further connecting bar 22 may be installed from the airbag 66to the front end 21 of the car.

The ignition of the igniters of the top airbag system 60 and bottomairbag system 64 is triggered by the sensor 6 in the bumper bar 5 in asimilar manner to the triggering of the airbag ignition in the bumpersystem according to Example 1.

The trigger signal is supplied via the sensor lines 12 to the airbagsystems 60 and 64.

The energy absorption in the middle part of the bumper is effected inthe manner illustrated in Example 1.

By virtue of the expansion of the top airbag 67 the flap 52 is opened—ina comparable manner to opening of the top flap in Example 1.

In the bottom part the expanded airbag 66 fills the bumper contour insuch a way that a uniform, kink-free front is produced. By said meansand by means of the top airbag 67 combined with the flap 52 the bucklingangle of the entire impact front is kept below 15° and the sheardistance is kept at less than 6 mm (see FIG. 3b).

Support of the bottom airbag 66 is effected in a comparable manner toExample 1 via a plastic/metal composite structure (polyamide/sheetsteel) attached to the cross-bar 10 or to the front end 21.

In the event of a crash, an anti-overload device in the optionallyadditionally provided connecting bar 22 provides protection against thedestruction or damage of built-on parts.

What is claimed is:
 1. A safety bumper for a motor vehicle comprising:(a) a bumper basic body having a forward surface; (b) a bumper bar; (c)a mounting member; (d) a cross-bar of the vehicle, said bumper bar beingconnected to said bumper basic body and extending through to the forwardsurface of said bumper basic body, said bumper bar also being connectedto said mounting member, said mounting member being located behind saidbumper basic body and said bumper bar, said mounting member beingconnected to said cross-bar, said cross-bar being located behind saidmounting member; (e) at least one of a deployable energy-absorbingelement positioned above said mounting member and a deployableenergy-absorbing element positioned below said mounting member; and (f)an impact sensor located in said bumper bar, wherein said deployableenergy-absorbing element is controlled by said impact sensor, uponactuation by said impact sensor said deployable energy-absorbing elementis deployed and forms a substantially continuous contour and asubstantially common front with the forward surface of said bumper basicbody.
 2. The safety bumper of claim 1 wherein said deployableenergy-absorbing element positioned above said mounting member is an airbag in a folded-up state, said air bag being located beneath a moveabletop bumper flap, said air bag comprising an igniter, and said igniterbeing electrically connected by a control line to said impact sensor,upon actuation of said igniter by said impact sensor the air bag deploysand together with said moveable top bumper flap forms a substantiallycontinuous contour and a substantially common front with the forwardsurface of said bumper basic body.
 3. The safety bumper of claim 1wherein said deployable energy-absorbing element positioned above saidmounting member comprises a lifting system connected to a drive, saidlifting system residing behind a sliding plate which abuts a moveabletop bumper flap, said drive being connected electrically by a controlline to said impact sensor, upon actuation of said drive by said impactsensor the lifting system deploys and together with said sliding plateand said moveable top bumper flap forms a substantially continuouscontour and a substantially common front with the forward surface ofsaid bumper basic body.
 4. The safety bumper of claim 1 wherein saiddeployable energy-absorbing element positioned below said mountingmember is an air bag in a folded-up state, said air bag being locatedbeneath a lowermost part of said bumper, said air bag comprising anigniter, and said igniter being electrically connected by a control lineto said impact sensor, upon actuation of said igniter by said impactsensor the air bag deploys and forms a substantially continuous contourand a substantially common front with the forward surface of said bumperbasic body.
 5. The safety bumper of claim 1 wherein said deployableenergy-absorbing element positioned below said mounting member is an airbag in a folded-up state, said air bag being located beneath a moveablebottom bumper flap, said air bag comprising an igniter, and said igniterbeing electrically connected by a control line to said impact sensor,upon actuation of said igniter by said impact sensor the air bag deploysand together with said moveable bottom bumper flap together forms asubstantially continuous contour and a substantially common front withthe forward surface of said bumper basic body.
 6. The safety bumper ofclaim 1 wherein said deployable energy-absorbing element positionedbelow said mounting member comprises a lifting system connected to adrive, said lifting system residing behind a bottom sliding plate whichis positioned under and abuts said bumper basic body, said drive beingconnected electrically to said impact sensor by a control line, uponactuation of said drive by said impact sensor the lifting system deploysand together with said bottom sliding plate forms a substantiallycontinuous contour and a substantially common front with the forwardsurface of said bumper basic body.
 7. The safety bumper of claim 3wherein the drive connected to said lifting system of said deployableenergy-absorbing element positioned above said mounting member is atleast one of a gas pressure cylinder and a hydraulic cylinder.
 8. Thesafety bumper of claim 6 wherein the drive connected to said liftingsystem of said deployable energy-absorbing element positioned below saidmounting member is at least one of a gas pressure cylinder and ahydraulic cylinder.
 9. The safety bumper of claim 2, 3 or 4 wherein saidmoveable bumper flap comprises a flexible plastic hinge connected tosaid bumper basic body.
 10. The safety bumper of claim 9 wherein saidflexible plastic hinge is fabricated from a material selected fromthermoplastic polyethylene and thermoplastic polyurethane.
 11. Thesafety bumper of claim 1 wherein said mounting member is one of astationary energy-absorbing plastic foam body and a stationaryenergy-absorbing plastic strut body.
 12. The safety bumper of claim 11wherein said stationary energy-absorbing plastic foam body is fabricatedfrom a material selected from polyurethane foam, polystyrene foam andpolypropylene foam.
 13. The safety bumper of claim 1 wherein saiddeployable energy-absorbing element is connected by means of asupporting strut to a front end of the motor vehicle.
 14. The safetybumper of claim 1 wherein said impact sensor can actuate said deployableenergy-absorbing element only when said motor vehicle is traveling a atspeeds of at least 8 kph.
 15. The safety bumper of claim 1 wherein saidimpact sensor can actuate said deployable energy-absorbing element onlywhen said motor vehicle is traveling a at speeds of at least 10 kph. 16.The safety bumper of claim 1 wherein said mounting member is astationary energy-absorbing mounting member.
 17. The safety bumper ofclaim 1 wherein the deployed energy-absorbing element together with theforward surface of said bumper basic body provide a buckling angle ofless than 15°.